The search for new sweeteners which are many times sweeter than sucrose and which are also non-caloric and non-cariogenic has been a continuing search for many years. In particular the search has been to provide new sweeteners which are not only many times sweeter than sucrose but which are free of the bitter aftertaste particularly associated with such artificial sweeteners as saccharine, and which in addition do not break down into products which are physiologically harmful and also which remain stable in aqueous systems and upon exposure to heat, for example during cooking.
U.S. Pat. No. 3,492,131 describes certain lower alkyl esters of L-aspartyl-L-phenylalanine which are up to 200 times as sweet as sucrose and which are free of bitter aftertaste. These compounds, however, possess only limited solubility in aqueous systems and are unstable due to diketopiperazine formation and hydrolysis especially in the neutral to acid pH range of most food systems (the diketopiperazine forms more slowly under acidic conditions).
European Patent Application No. 0034876, published Sept. 2, 1981, describes branched amides of L-aspartyl-D-amino acid dipeptides as sweeteners. These compounds are stated as being free of undesirable flavor qualities at conventional use levels and as having high stability both in solid form and in aqueous systems. The breakdown products thereof are not given so that the final possible uses of these sweeteners are not yet known.